JPH06235422A - Rotation shaft deviation correction control device - Google Patents

Abstract

PURPOSE:To provide a rotation shaft deviation correction control device which can highly accurately measure in real time axis deviation of a rotation shaft rotating at high speed regardless of a shape of a reference ring to suppress the axis deviation at a low value so as to enhance rotary motion accuracy. CONSTITUTION:This device is provided with a reference ring 14 fixed concentrically with a rotation shaft 4 to an end thereof, three proximity sensors 16 arranged in a row on a circumference of the reference ring 14, and a controller 18 for successively measuring an axis deviation locus of the rotation shaft 4 by means of a three-point problem based on measured data of the proximity sensors 16, and separating the measured data to fitting direction component data of a piezo-actuator to control the piezo-actuator based on these data. A bearing clearance of an air bearing is thus controlled in accordance with the axis deviation locus obtained in real time by the three-point problem, and axis deviation of the rotation shaft 4 rotating at high speed can be thereby suppressed at a low value and a rotary motion mechanism with extremely high accuracy can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary shaft shake correction control device for accurately measuring the shaft runout of a high speed rotary shaft lubricated by an air bearing and correcting the rotary motion to a perfect circle as much as possible. is there.

[0002]

2. Description of the Related Art In a rotary motion mechanism element such as a turning machine, its rotational accuracy is directly related to the machining accuracy of a workpiece. Therefore, if highly accurate machining is to be performed, at least the rotational motion should be measured and the axial center runout should be as great as possible. Need to be controlled so that

As a method of measuring the rotational accuracy of a rotary motion mechanism element, particularly a rotary shaft supported by bearings, a reference sphere or a reference ring is used as the rotary shaft, and its center of gravity is made to coincide with the center of rotation of the rotary shaft. And attach one proximity sensor to each of the x-axis and the y-axis on the circumference of the outer wall of the reference ring or the reference sphere perpendicular to the axis of the rotating shaft, and rotate the rotating shaft at a constant speed. A method of measuring the rotational motion accuracy by measuring the distance from the reference sphere or the outer wall surface (surface) of the reference ring by a proximity sensor on the table is often used.
When a Lissajous figure is drawn based on the distance data in the x direction and the y direction thus measured, the radius difference between the circumscribed circle and the inscribed circle of the Lissajous figure becomes equal to the axial runout of the rotary motion element.

Further, as the correction control of the motion error of the rotating shaft, a signal which is feedback-controlled based on the measured shaft center runout is sent to the controller of the hydraulic servo valve,
By changing the bearing clearance between the air bearing and the rotating shaft by hydraulic pressure,
A method is used in which the axial runout locus is reduced by controlling the air pressure to improve the rotational motion accuracy.

[0005]

However, as described above, in the case of measuring the axial runout of the rotating shaft using the reference sphere or the reference ring, the center of gravity of the reference sphere or the reference ring and the axis of the rotating shaft are measured. It is necessary to match the cores, but it is extremely difficult to match them, and measurement error is unavoidable. In addition, the rotational accuracy of the rotary shaft is very high, and the shape accuracy of the reference sphere, that is, when the shape accuracy of the reference sphere approaches, it becomes impossible to detect the shape error of the reference sphere and the rotational motion error separately. Measurement accuracy is limited. In addition, due to the eccentricity of the center of gravity of the reference ring, it is not always possible to immediately know the runout of the rotary shaft from the Lissajous figure obtained from the measurement data, and it is difficult to measure the rotary motion accuracy during processing in real time.

Further, in the conventional correction control of the rotational movement error of the rotating body by the hydraulic pressure, it is effective for the control of the low speed rotation of about several tens of rpm, but the rotational movement control of the several thousand rpm which is usually used in the air bearing etc. Can not follow the speed of shaft runout.

Therefore, in the conventional measurement of the shaft runout of the rotary shaft and the correction control of the rotational motion error of the rotating body, the measurement of the shaft runout of the rotating shaft rotating at high speed and the rotary shaft runout correction control are performed with high accuracy. The problem was that it was difficult.

The present invention solves the above problems,
Feedback control that measures the axial runout of the rotating shaft of the air bearing that rotates at high speed of several thousand rpm in real time with high accuracy regardless of the accuracy of the shape of the reference sphere or the reference ring, and suppresses the runout It is an object of the present invention to provide a rotation axis shake correction control device capable of increasing the rotational motion accuracy by performing the rotation at high speed.

[0009]

In order to solve the above problems, a rotary shaft shake correction control apparatus of the present invention is a rotary shaft shake correction control in an air bearing for changing a bearing gap between the rotary shaft and the rotary shaft by expanding and contracting a plurality of piezoelectric actuators. A device,
A reference ring mounted on one end of the rotary shaft with its axis aligned, three proximity sensors arranged in a line on the circumference of the cylindrical surface of the reference ring, and the proximity sensor measures. The axial deviation trajectory of the rotary shaft is sequentially measured based on the displacement data based on a three-point method, the measurement data is separated into attachment direction component data of the piezo actuator, and the piezo actuator is determined based on the attachment direction component data. It is characterized in that a control means for driving is provided.

[0010]

With the above construction, when the axis deviation trajectory of the rotary shaft measured by the three-point method deviates from the bearing center, the deviation amount from the bearing center is separated into components in the piezo actuator mounting direction, and according to this component amount. By expanding and contracting each piezo actuator, changing the bearing clearance, and controlling the air pressure of the bearing, it is corrected so that the axis runout locus of the rotating shaft becomes smaller.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a two-row air supply type radial static pressure air bearing having a large number of air supply holes of an orifice throttle using the rotary shaft shake correction control device of the present invention, and FIG.
-A sectional view, FIG. 3 is a BB sectional view of FIG.

1 to 3, reference numeral 1 is an air bearing having eight air supply holes 2 arranged in two rows in the circumferential direction.
The rotary shaft 4 is lubricated by the high-pressure air supplied from the rotary shaft 4. Further, 5 is a bearing casing for fixing the air bearing 1, and an air supply groove 6 for supplying the high pressure air 3 to the air supply hole 2 of the air bearing 1 is formed on the circumference so as to include the inlet of the air supply hole 2. The air supply groove 6 is entirely connected to the air supply port 7. Further, the space sandwiched between the two air bearings 1 and the bearing casing 5 is the exhaust groove 8, and the high pressure air 3 that enters from the air supply port 7 and passes through the air supply hole 2 and flows out from the bearing gap is exhausted. It works to lead to 9. Further, 10 is a groove for arranging the piezo actuator 11 for correcting and controlling the bearing gap,
Two piezo actuators 11 are arranged in the groove 10 in the x-axis and y-axis directions. Further, 12 is a thrust bearing for receiving a force in the thrust direction of the rotary shaft 4, and each of the thrust bearings 12 has an air supply hole 13 communicating with the air supply port 7.
Are provided on the circumference of the bearing surface. Reference numeral 14 denotes a reference ring fixed to the end of the rotary shaft 4 at the end of the rotary shaft 4 so as to match the center of gravity thereof in order to measure the radial runout of the rotary shaft 4. It has a high roundness near the mirror surface.

Further, the air bearing 1 is formed with hollow holes 15 on both sides of the air supply hole 2 in the positive direction of the x-axis and the negative direction of the y-axis in its cross section. A part of the inner wall and the outer wall of the bearing 1 is formed in a leaf spring structure, and the bearing gap is controlled by operating this region by expanding and contracting the piezo actuator 11 from the outside.

Further, as shown in FIG. 4, three proximity sensors 16 supported by an arcuate jig 16A are arranged in a line on the circumference of the cylindrical surface of the reference ring 14, The displacement signals measured by these proximity sensors 16 are input to a proximity sensor amplifier 17, amplified by this proximity sensor amplifier 17, and a controller 18 including a microcomputer is provided.
Entered in. The controller 18 calculates the axial runout amount of the rotary shaft 4 based on the measurement principle of the three-point method based on the input displacement signal, and the eccentric components in the x-axis and y-axis directions, which are the mounting directions of the piezo actuator 11. Separated into this x
A control signal for zeroing the eccentricity components in the axial and y-axis directions is output to the piezo actuator driving device 19. The piezo actuator driving device 19 expands and contracts the x-axis and y-axis piezo actuators 11 according to the control signal.

These proximity sensor 16 and proximity sensor amplifier 1
By driving the piezo actuator 11 whose response time is extremely fast by the output of the correction control device including the controller 7, and the piezo actuator drive device 19, the bearing clearance of the air bearing 1 is controlled at high speed and the rotation speed is high. The shaft runout of the shaft 4 can be kept small,
It is possible to realize a highly accurate rotary motion mechanism.

However, in the three-point method, since the axial runout amount and the shape data of the reference ring 14 are extracted from the displacement signal measured by Fourier series expansion, real-time axial runout measurement control is difficult. Therefore, prior to the axial runout measurement control, the positional relationship between the shape data of the reference ring 14 and the three-point measurement proximity sensor 16 in the radial direction is obtained, and at the time of control,
The shape data of the reference ring 14 and the positional deviation amount of the proximity sensor 16 are subtracted from the measurement data from the three proximity sensors 16, and the piezo actuator 11 is driven by using the shaft center shake amount thus obtained. This arithmetic processing is simple subtraction and multiplication, and by using a microcomputer, real-time control can be sufficiently performed for rotation of about 8000 rpm.

The present invention is based on the piezo actuator 11
Are mounted in the x-axis and y-axis directions, but they can be mounted at any angle, and two or more units can be mounted. At this time, the axial runout amount is separated into eccentric components according to the mounting direction of the piezoelectric actuators 11 and the number of the piezoelectric actuators 11. Further, it goes without saying that the present invention can be applied to a low speed rotary motion mechanism such as a roundness measuring machine.

[0018]

As described above, according to the present invention, when the axial runout locus of the rotary shaft measured by the three-point method deviates from the bearing center, the deviation amount from the bearing center is changed in the mounting direction of the piezo actuator. By separating the components, expanding and contracting each piezo actuator according to the amount of this component, changing the bearing clearance, and controlling the air pressure of the bearing, there is no response delay as in the past, and the axis of the rotating shaft is at high speed. The shake locus can be corrected to be small, and an extremely highly accurate air bearing can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram of a rotary shaft shake correction control device according to the present invention,
FIG. 3 is a cross-sectional view of a two-row air supply type radial static pressure air bearing having a large number of air supply holes of an orifice throttle.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG.

FIG. 4 is a configuration diagram of a rotation axis shake correction control device of the present invention.

[Explanation of symbols]

 1 Air Bearing 2 Air Supply Hole 3 High Pressure Air 4 Rotating Shaft 5 Bearing Casing 6 Air Supply Groove 7 Air Supply Port 8 Exhaust Groove 9 Exhaust Port 10 Piezo Actuator Mounting Groove 11 Piezo Actuator 12 Thrust Bearing 13 Air Supply Hole 14 Reference Ring 15 Cutout 16 Proximity sensor 17 Proximity sensor amplifier 18 Controller 19 Piezo actuator drive

Claims (1)

[Claims] 1. A rotary shaft runout correction control device in an air bearing for changing a bearing clearance between the rotary shaft and the rotary shaft by expanding and contracting a plurality of piezoelectric actuators, wherein the reference is mounted at one end of the rotary shaft such that the shaft centers thereof are aligned with each other. A ring, three proximity sensors arranged in a row on the circumference of the cylindrical surface of this reference ring, and displacement data measured by this proximity sensor, based on the three-point method, the axis deviation of the rotary shaft. Rotational axis shake correction, characterized in that a control means for sequentially measuring a locus, separating the measured data into mounting direction component data of the piezo actuator, and driving the piezo actuator based on the mounting direction component data is provided. Control device.